Organic electronic devices based on organic electroluminescence (abbreviated as organic EL, hereinafter), organic solar cell, for example, have attracted public attention. In these sort of devices, transparent surface electrode has been understood as an indispensable component technology. Conventionally, ITO transparent electrode, composed of an indium-tin composite oxide (ITO) film formed on a transparent substrate by vacuum evaporation or sputtering, has been used as the transparent surface electrode, by virtue of its performances including electroconductivity and transparency.
The transparent electrode formed by vacuum evaporation or sputtering has, however, been suffering from high manufacturing cost due to poor productivity. In addition, the ITO transparent electrode has been becoming insufficient in resistivity, in view of satisfying recent demands for larger area of the organic electronic devices.
In view of satisfying such large-area organic electronic devices, there has been developed transparent electrodes configured by stacking a patterned electroconductive layer composed of a metal with a polymer electroconductive layer composed of an electroconductive polymer and such like, the transparent electrode characterized by high electroconductivity and excellent in-plane uniformity of electric current (see Patent Literatures 1 and 2, for example).
Possible methods of forming a patterned metal include a method based on physical development of silver halide particles, a method for forming a metal foil on a substrate followed by etching, and a method for printing a metal particle according to a predetermined pattern by gravure printing on a transparent substrate and the like (see Patent Literatures 3 and 4, for example). Among these methods, the method for forming the metal pattern by printing is thought to be an excellent method in view of economy and productivity.
However, the transparent electrode composed of a patterned metal electroconductive layer formed by printing and the polymer electroconductive layer composed of an electroconductive polymer stacked on the patterned metal electroconductive layer has been suffering from high frequency of current leakage, poor storability under high-temperature atmosphere, and insufficient durability against bending, when applied to the organic electronic devices.